This application responds to PA-03-015, which supports preliminary studies to demonstrate the feasibility of novel research approaches. It has a 10-page limit and limited budget. The present application investigates a novel approach to increasing physical activity levels. Physical activity is beneficial for health; however, most Americans are sedentary. Recently, there has been interest in whether the physical environment can influence activity levels among large numbers of people. The available data have two main limitations. First, the data come primarily from land use and transportation research, using cross-sectional studies. These data indicate an association between the built environment and choice of transportation (car, bus, walk, etc.). However, it is unclear whether the built environment influences physical activity, or whether active persons prefer living in a particular built environment. Second, studies from public health research, with similar findings, have used self-reports of the physical environment. These results may be biased by active persons being more aware of facilities which encourage exercise (e.g., parks, shops within walking distance, etc.). The present study investigates the association between the physical environment and physical activity, addressing the limitations above. It will test the primary hypothesis that persons living in areas with less urban sprawl have higher levels of physical activity. Date from the Harvard Alumni Health Study (HAHS) and the Trials of Hypertension Prevention Follow-up Study (TOHP) will be used. HAHS comprises about 10,000 men who returned health surveys in 1988 and 1993. TOHP comprises about 3,300 men and women who returned health surveys in 1988-95 and again in 1999-2004. An objective measure of urban sprawl will be assigned to each subject, at each of the two time points, using subjects' addresses and GIS mapping. An urban and transportation planner will provide expertise on urban sprawl measures. In both studies, physical activity was assessed using validated questions on walking, climbing stairs, and leisure activities. Cross-sectional and longitudinal analyses will be conducted. A pilot study in HAHS indicated that 16% of men changed addresses between 1988 and 1993. Examining persons who move will minimize bias from active persons who choose to live in areas with less urban sprawl. This study will provide important information for planning or redesigning communities in order to maximize the potential for physical activity and health.